getGroups.corStruct           package:nlme           R Documentation

_E_x_t_r_a_c_t _c_o_r_S_t_r_u_c_t _G_r_o_u_p_s

_D_e_s_c_r_i_p_t_i_o_n:

     This method function extracts the grouping factor associated with
     'object', if any is present.

_U_s_a_g_e:

     ## S3 method for class 'corStruct':
     getGroups(object, form, level, data, sep)

_A_r_g_u_m_e_n_t_s:

  object: an object inheriting from class 'corStruct' representing a
          correlation structure.

    form: this argument is included to make the method function
          compatible with the generic. It will be assigned the value of
          'formula(object)' and should not be modified.

   level: this argument is included to make the method function
          compatible with the generic and is not used.

    data: an optional data frame in which to evaluate the variables
          defined in 'form', in case 'object' is not initialized and
          the grouping factor needs to be evaluated.

     sep: character, the separator to use between group levels when
          multiple levels are collapsed.  The default is ''/''.

_V_a_l_u_e:

     if a grouping factor is present in the correlation structure
     represented by 'object', the function returns the corresponding
     factor vector; else the function returns 'NULL'.

_A_u_t_h_o_r(_s):

     Jose Pinheiro Jose.Pinheiro@pharma.novartis.com and Douglas Bates
     bates@stat.wisc.edu

_S_e_e _A_l_s_o:

     'getGroups'

_E_x_a_m_p_l_e_s:

     data(Orthodont)
     cs1 <- corAR1(form = ~ 1 | Subject)
     getGroups(cs1, data = Orthodont)

